This invention relates to an apparatus for treating powdery, granular and conglomerate materials and an analyzing method using the apparatus.
In analyzing components of various materials by a method such as the X-ray fluorescence analysis, it is necessary to pretreat the material to be analyzed.
The following four methods have been known as methods for making samples of inorganic materials.
(1) A crushing method in which a material is pulverized in order to bring the material into an appropriate condition for the analysis. PA1 (2) A vitrifying method in which a material is added with one or a mixture of an alkali metal borate (for example. Li.sub.2 B.sub.4 O.sub.7, Li.sub.2 O.B.sub.2 O.sub.3 and Na.sub.2 B.sub.4 O.sub.7) and heated to be vitrified. PA1 (3) An alkali metal carbonate decomposing method in which a material is decomposed by an alkali metal carbonate. PA1 (4) A decomposition solution method in which a material in a pressurized vessel is decomposed by a strong acid such as hydrofluoric acid to make it a solution.
The crushing method, among the above methods, is disadvantageous because if the material is at least partially crystalline, the crushed material still includes a crystal structure so that analyzed results with high accuracy could not be obtained in the X-ray fluorescence analysis due to the socalled "mineral effect". Moreover, it takes a long time to crush inorganic materials including non-oxides as components such as silicon nitride, sialon, silicon carbide and the like owing to high hardness. Moreover, there is a risk that the materials may be contaminated by a material of a vessel used for crushing. Therefore, the crushing method has been scarcely used other than in cases not requiring a high accuracy of analysis.
The alkali metal carbonate decomposing method is applicable as a pretreatment method for wet analyses, even for non-oxides. However, this method could not be used for pretreating materials for the X-ray fluorescence analysis due to the fact that decomposed and melted products are high in moisture absorption and are difficult to be removed from used vessels such as platinum dishes and the like.
The vitrifying method, using the alkali metal borate, is disadvantageous because analyzing accuracy is often lowered since vitrification only partially progresses in the case of inorganic materials including non-oxides as components.
Moreover, the decomposition solution method using a strong acid requires a long time (such as 24 hours) for the decompositions. Samples obtained for the analysis are liquid which is preferable for the chemical analysis. However, it is difficult to use such liquid samples in the X-ray fluorescence analysis because of a limitation of an apparatus itself for the X-ray fluorescence analysis.
The so-called "mineral effect", which means that the grain sizes of samples detrimentally affect the accuracy of analysis of the samples, has been known. In order to avoid the mineral effect to carry out the analysis with high accuracy, it is necessary to pulverize samples in powdery, granular and conglomerate states into fine powders of the order of less than 1 .mu.m and to form formed bodes suitable for analysis. It is preferred that the formed bodies have smooth surfaces for high accuracy analysis. Moreover, it is desired that the formed bodies are rigid and stable for a long period of time in order to facilitate the operation and automation for the analysis. The crushing to forming processes are referred to herein as "pretreatment of samples for the X-ray fluorescence analysis".
The pretreating methods for the X-ray fluorescence analysis have been known as non-addition dry crushing and non-addition wet crushing methods which are carried out in dried and wet conditions without any additions, powdery graphite added dry crushing which is carried out in a dried condition with added graphite (magazine of Japanese Metallurgy Society, vol. 36, page 648, 1972), and binder added wet crushing which is carried out in a wet condition with binders such as styrene-maleic acid copolymer or stearic acid. The powdery graphite has a lubricating effect so that it is effective as a crushing aid for promoting pulverization of samples. On the other hand, binders are effective as a forming or molding aid which gives strength to formed bodies and makes smooth surfaces of the formed bodies. Graphite is also somewhat effective as a molding aid. However, the effect of graphite as the molding aid is insufficient for disk-like formed bodies having diameters of more than 10 mm which are usually used for the X-ray fluorescence analysis.
Although the above non-addition dry crushing method is simple in operation, it is disadvantageous since crushing is sometimes insufficient, analyzing accuracy is lowered due to the mineral effect, and forming samples into disk-like bodies is difficult. The non-addition wet crushing method is disadvantageous since analyzing accuracy is lowered, forming samples into disk-like bodies is difficult and, moreover, since volatilization of solvents is needed. The powdery graphite added dry crushing method is disadvantageous since forming samples into disk-like bodies is difficult, although there is no problem of lowering the analyzing accuracy due to the mineral effect. The binder added wet crushing method is disadvantageous since there is a problem of lowering the analyzing accuracy due to the mineral effect and volatilization of solvents is needed. Therefore, a pretreatment method of samples for X-ray fluorescence analysis has not been proposed, capable of obtaining formed bodies which will bring high accuracy analysis and are rigid and smooth.
In order to supply powdery, granular or conglomerate materials to predetermined positions such as crushers, weighed materials have been manually supplied from hoppers at the predetermined positions to apparatuses such as crushers.
Manual supplying requires skillful operators and obstructs automation of the entire installation line. An automated apparatus, for example, Model HSM-F36 of the HERZOG Company, has been known which comprises, in the proximity of materially supplied positions, a turn table having material vessels provided along a circumference of the turn table, and introducing means for intermittently rotating the turn table.
In such an apparatus, however, the material is supplied into the hoppers with the aid of centrifugal forces caused by rotation of the material vessels driven by the introducing means. Therefore, all the materials could not be supplied into the hoppers exactly. Moreover, the turn table is disadvantageous since material is introduced into the hoppers only in a predetermined order due to the fact that the turn table performs its intermittent rotation only in connection with the material vessels.
Various crushers for crushing samples have been known. With these crushers, a crushing operation is carried out with crushing vessels made of, for example, tungsten carbide (WC) regardless of whether the operation is manual or automatic.
In this case, introduction of samples and removal of crushed samples are effected by transferring crushing vessels from the crushers to working tables. Every time kinds of samples are changed, the crushing vessels mush also be transferred from the crushers to the cleaning means for cleaning the vessels. These troublesome transferring of the vessels have been manually carried out.
The vessels made of tungsten carbide or chromium steel are so heavy that the manual operation for transferring the vessels is disadvantageous to safety and efficiency. On the other hand, when organic binders are added to samples to be crushed, the binders are likely to stick to inner walls of the crushing vessels. Therefore, the attached crushed samples could not be completely removed from the crushing vessels without manual cleaning.
In various analyzing apparatuses, particularly the fluorescent X-ray analyzing apparatus, these apparatuses have been supplied with samples to be analyzed as formed bodies in predetermined shapes or accommodated in predetermined exclusive holders. In order to make such formed bodies of samples or insert samples into the holders, separate pressing apparatuses or holder loading and unloading apparatuses are needed.
In this case, the precise X-ray fluorescence analysis for various kinds of samples is accomplished by manually operating the formation of the samples and transference of the samples to the apparatuses. However it is impossible to automatically supply the samples to fluorescence X-ray analyzing apparatuses to form automatic analyzing systems. Moreover, when existing holder loading and unloading apparatuses are used, only one or two reference samples are held at a time. Therefore, such existing apparatuses could not be used for automatically analyzing various kinds of samples continuously and precise X-ray fluorescence analysis could not be realized, so that the use of the existing apparatuses is limited to particular analyses. Such a limitation of use results also from the fact that the holders are prohibitively expensive and particular. Thus, they could not be provided in large quantities.
In order to determine predetermined compositions in samples, the X-ray fluorescence analysis with X-ray has been used and various fluorescent X-ray analyzing apparatuses have been known. With such fluorescent X-ray analyzing apparatuses, in supplying a sample to the apparatus the sample must be formed in a predetermined shape and set at a predetermined position in a sample holder. Moreover, the sample must be pretreated in order to avoid the influence of physical and chemical factors of the sample on fluorescence X-ray intensity and to improve the analyzing accuracy.
For this purpose, in the case of inorganic samples such as ceramics or the like, it is required to use a crusher for crushing an inorganic raw material into predetermined grain sizes and a press for forming the crushed material into predetermined shapes. Thus, produced samples are set in the sample holder for the X-ray fluorescence analysis.
With hitherto used apparatuses, introducing the samples into the apparatuses is not reliably effected. Transferring the samples between the apparatuses and setting the samples into the apparatuses must be effected by skillful operators. Further, even with new systems partially automated with such operations, it might be ineffective, if not impossible, to carry out various kinds of samples.